"Rocky is one of the biggest parks in terms of visitation," said Joan Anzelmo, volunteer and spokeswoman for the Coalition of National Park Service Retirees.

About 220,000 people visited Rocky Mountain National Park last October, Visit Estes Park spokeswoman Suzy Blackhurst said. That estimate is based on Park Service data, which does not break down visits by day or week, she said.

Rocky Mountain National Park, along with the other 400 national parks, was closed Oct. 1 when the government failed to pass a budget.